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Codex is one of the most important untold stories in the history of technology.

A year ago, OpenAI’s coding effort looked lost in the wilderness:

Codex Cloud had flopped.
Their $3 billion Windsurf deal fell apart.
Claude Code was running away with the market.

Less than 12 months later, a tiny team in the “backwaters” of OpenAI built an app that grew to more than 40 million users, swallowed ChatGPT from the inside, and remade the entire company.

I had a front-row seat to the whole arc—from a conference room in their office the night before GPT-5 launched to the day Codex took over ChatGPT—and spent months interviewing the people who made it happen, including OpenAI’s Greg Brockman and Thibault “Tibo” Sottiaux. It’s a wild story about what it takes to build when the frontier is moving beneath your feet:

Read ‘How Codex Happened’

Your free Every account includes 10 prompts for applying lessons from the story to your own work and the story as a PDF.

The story is also completely agent-native. Paid members get the full transcripts of all six of my interviews with OpenAI insiders, and a live session with me tomorrow about how we reported and wrote the story with Codex and what I learned about how OpenAI came back.

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Dan Shipper is the cofounder and CEO of Every, where he writes the Chain of Thought column and co-hosts The Every Podcast. You can follow him on X at @danshipper and on LinkedIn.